Author Topic: cracked head (Read 5296 times)

Isamemon · « **on:** January 04, 2009, 01:03:41 PM »

pulled my head and found it was cracked. Found a aluminum head rebuilder that is about an hours drive away
says cracks are no problem
http://www.aluminumheads.com

30 to pressure test
50 an hour to fix crack
32 to plane head
86 to grind all valves and seats

does this all sound reasonable

nomad · « **Reply #1 on:** January 04, 2009, 01:29:14 PM »

sounds good but what are they guaranteeing?
I'm interested in this now too since I have two cracked heads sitting here. Ask them what the typical time estimate is - 6 hours?

you have this:

or this:

Nomadic · « **Reply #2 on:** January 04, 2009, 02:45:47 PM »

That quote sounds like you are dissembling/reassembling the head.... correct? The website lists rebuilt m42/m44 heads at $550 & $275 core.

It will also depend on the severity and location of the crack. Post some pics.

Also remember that the cams will snap if the caps are removed incorrectly....

KenC · « **Reply #3 on:** January 06, 2009, 01:34:23 PM »

They rebuilt the entire exhaust side of my head. I think it was like $250-300 including labor. You have to remove the cams and retainers before you bring it to them.

Give Joe at Autobahn Sport a call too... I think he may have a good used head.

Cobra Jet · « **Reply #4 on:** January 07, 2009, 01:09:52 PM »

I'd like to know how they repair such cracks, because in some instances, the crack is not just on the surface, as there is the very possibility that the crack has traveled further up into the head... in such an instance, HOW is that even repairable (my guess is, it is not repairable and the head is junk)...

post up more info as to how the shop intends to fix your cracked head and if possible, post pics of your cracked head.

Most of the cracked M42 heads are of the (2) varieties posted above by Nomad... the second pic, that crack seems to be the most common of the two and in most instances is not just a surface crack.

nomad · « **Reply #5 on:** January 08, 2009, 06:47:21 PM »

I agree above:

In the two pics I posted, the one without the valves was cleaned and looked at by a head specialist. He pulled the valve and used a wire wheel to clean up the passage when it became really clear the crack went through the whole head into the passage a good ways. The valve seat you see is steel so that's not cracked. He said he could not fix it because it was too extensive, another send off place "might" try it.

he explained that to repair a crack they have to grind the crack out, meaning grind a slot where the crack is and keep grinding until there is no longer a crack (won't work if the crack goes all the way through) then they weld in aluminum until it is all built back up. They can then re-machine the area and put it all back.

My guess is that the second head I have that is cracked (thanks to a lousy forum seller) has the crack all the way through as well.

it was easier and more efficient for me to get another head.

bmwpower · « **Reply #6 on:** January 08, 2009, 07:51:31 PM »

Mine went up into the jacket. Not sure how high but enough to make it a door stop.

Don't friggin overheat these heads people!

If there was a product that could fuse the crack without welding, that would be nice. Epoxy? JB Weld?

nomad · « **Reply #7 on:** January 08, 2009, 10:50:26 PM »

maybe i should keep a spare

Isamemon · « **Reply #8 on:** January 09, 2009, 09:36:13 PM »

my crack is really bad too, so IM still searching for a head

1991 E30 M42 · « **Reply #9 on:** January 09, 2009, 10:08:10 PM »

Quote from: Cobra Jet;64285

I'd like to know how they repair such cracks, because in some instances, the crack is not just on the surface, as there is the very possibility that the crack has traveled further up into the head... in such an instance, HOW is that even repairable (my guess is, it is not repairable and the head is junk)...

post up more info as to how the shop intends to fix your cracked head and if possible, post pics of your cracked head.

Most of the cracked M42 heads are of the (2) varieties posted above by Nomad... the second pic, that crack seems to be the most common of the two and in most instances is not just a surface crack.

They will grind the crack out, they can go pretty deep, then the weld it up and grind away excess/reshape the combustion chamber, then they will resurface the the entire head so it has a uniform deck height

1991 E30 M42 · « **Reply #10 on:** January 09, 2009, 10:12:29 PM »

Quote from: nomad;64355

maybe i should keep a spare

Thats what I do, I also have a place near me that rebuilds heads for $200

Isamemon · « **Reply #11 on:** January 10, 2009, 12:33:19 AM »

the crack is like the first one in the pics by nomad
I heard through the grape vine that the frist place I mentioned above is one to stay away from
my local shop is going to do the work, but the head has to be sent to another person to weld as the crack goes deeper then my main shop can handle
in fear of what this is now gonna cost is why I am also looking for a good head with no cracks
I have had mixed pms on various forums on if the "repaired" heads are reliable

but I am running out of options and will most likely have to gamble on the head getting fixed correctly

nomad · « **Reply #12 on:** January 10, 2009, 08:50:50 AM »

Quote from: Isamemon;64398

but I am running out of options and will most likely have to gamble on the head getting fixed correctly

Why?
Buy the head I have...

Isamemon · « **Reply #13 on:** January 10, 2009, 10:48:25 AM »

arent yours cracked also ?

nomad · « **Reply #14 on:** January 10, 2009, 11:35:20 AM »

Sorry if i was unclear... Check my for sale thread for pics.
I have one good head for sale.

I posted pics of the two cracked heads I have sitting in my garage from when I had to replace my own a year ago. When I was looking it took me a while to find a replacement, along the way I had the fun experience of buying a head from a forum guy that "thought it was fine" but turned out to be cracked... that's why I have two nice doorstops.